The Fenian brotherhood was an Irish-American secret society organized in 1859 in New York to assist in the movement towards Ireland's independence. They were men still looking for a cause. Many were returning Irish soldiers from the American Civil War. Their leader was a "General" John O'Neill. In fall of 1871 they tried to mount a raid on newly created province of Manitoba. The Fenians had developed a plan to invade Canada after their effort to create an uprising in Ireland had failed. They wanted to establish a base of operations in Canada against Britain. And somehow they thought they would be welcomed as liberators from British rule.

They tried to invade Fort Erie in June of 1866. And two days later they attacked the eastern townships of Quebec. A man called William O'Donoghue, Riel's colleague in the Riel rebellion, was behind the raid on Manitoba. O'Donoghue was expecting the disaffected Metis of Manitoba to back his plan of taking over Manitoba. He had already urged Riel to join the US as early as 1869. O'Donoghue had moved to New York as a little boy and had seen the Irish famine and the 1848 Young Ireland rebellion firsthand. He hated the British and had a strong feeling of Irish patriotism.

O'Donoghue came to Manitoba with Bishop Grandin in 1868 to teach mathematics at the St. Boniface College. In 1869 he became involved with the Red River Rebellion and served as treasurer in Riel's provisional government. Riel and O'Donoghue had a falling out because O'Donoghue thought Riel was being too compromising to the British. In 1871 O'Donoghue took a secret petition to Ulysses S grant asking him to intervene. When the president refused to act O'Donoghue turned to the Fenians and organized a party of unemployed labourers in Minnesota. He planned to take over Manitoba and set up a the Republic of Rupert's Land with himself as president.

Riel was in fact against the US attack, and warned Lieutenant Governor Adams Archibald about it. Rumours said 2,000 Fenians were ready to invade Manitoba. This was enough to cause the Hudson Bay Co Factor at the Pembina post to pack up and flee. On Oct 3, 1871, Archibald issued a proclamation asking for volunteers to help protect Manitoba. The response was immediate and hundreds of men came forward including the entire colony of Kildonan which turned out to a man. The Metis community also turned out well with Riel and Lepine heading a body of cavalry.

And on a fall cold and rainy day, the Manitoba men spent two days in a muddy march south through St. Norbert and St. Agathe that miserable weekend to face the invading enemy from the US. O'Donoghue and O'Neill accompanied by 35 men, crossed the border on October 5, 1871 and took over the Hudson Bay Post at Pembina North Dakota. Col Lloyd Wheston Commanding the US Army in Pembina sent a telegram to US consul J W Taylor advising that General O'Neill, had been captured and that further anxiety regarding a Fenian invasion of Manitoba was unnecessary. O'Donoghue got away but was soon captured by a group of Metis riders and taken back to Minnesota.

There were no casualties! There had been no battle. The Canadians and the Fenians never even met. The border has been free from attack ever since. The Fenian Raid remains one of those hiccups in history between two great nations. O'Donoghue did not have charges laid against him, although he was banned from Manitoba for a few years. He returned to the United States settling in Minnesota and died of tuberculosis in 1878 at age 35.